Various immunoassay test methods and apparatus are known in the art. Typical test apparatus such as the one described in U.S. Pat. No. 4,623,901, use a multilayer construction to perform varying functions, for example, a first layer serves to entrap particles such as the antibody specific to the immunoassay technique, a second layer controls the flow of the liquid through the test apparatus and a third layer provides an absorbent for the liquid sample at the bottom of the kit. This multilayer construction, however, increases the number of steps of the process, increases the size of the kit and also increases the number of manufacturing steps required to assemble the kit.
These multilayers are typically made of fibers of nylon, glass, polyester, polyolefins and cellulose acetate. Fibrets of cellulose organic esters, however, heretofore have not been combined with dispersible cut fibers to form filter materials in general, and specifically have not been combined to form a support element used in an immunoassay process. Fibrets of cellulose organic esters and particularly cellulose acetate have been used for lightweight paper products such as those adaptable for uses as tobacco smoke filters, industrial air filters and filters for organic compounds.